As far as I know, Lisinopril is for blood pressure, not for blood sugar. Are you hypertensive? ok quick google/wikipedia says it is used for prevention of renal and retinal problems in diabetics...

I was given lisinopril and did fine for a few months, but did develop a horrible cough about 3 months later, I wasn't sure if it was from the med or a reaction from a cold/virus that I'd been trying to recover from. The cough was worst when I was talking on the phone, which was very weird for me. Most of my post-cold coughs were bad at night, and this one was, but the phone-speak-cough was just awful. I eventually ditched all new meds, got some prednisone (doc prescribed) and went back to my metoprolol, no more cough.

ACE inhibitors are known for causing a dry cough. I agree with MrsD, get it checked out and see about getting your med switched to something else.